1. Field of the Invention
This invention relates to a suspension position sensor for a vehicle, as well as to a method of calibrating such a sensor.
2. Disclosure Information
Vehicular suspensions employing adjustable suspension units typically utilize one or more sensors for detecting the position of one or more portions of the suspension with respect to either another part of the suspension itself or another part of the chassis of the vehicle. In other words, suspension position sensors are used to detect the vertical position of the roadwheels with respect to the chassis of the vehicle. In the case of vehicles using load leveling or air or hydropneumatic suspension systems, it is necessary to know the ride height of the vehicle to determine whether correction of the ride height is required. In the event, for example, that the ride height is lower than a prescribed "trim" limit, as determined by the height sensor, an adjustable suspension unit may be given a command to increase ride height. Conversely, in the event that the ride height exceeds the prescribed "trim" limit, the adjustable suspension unit may be given a command to lower, or decrease, the ride height.
In order to provide reliable information to the suspension unit, the height sensor must be calibrated. This involves ensuring that the output of the sensor corresponds to the correct vehicle ride height or wheel position with respect to the chassis of the vehicle. U.S Pat. No. 4,555,120 discloses a commonly employed type of suspension position sensor which must be mechanically adjusted to synchronize the sensor's output with the actual vehicle ride height. U.S. Pat. No. 4,105,216 discloses a motor vehicle level control circuit in which a pair of optical detectors interacts with a rotary shutter device to produce a first logic signal pair when the vehicle's ride height is in a trim region, and second and third logic signal pairs when the vehicle's ride height is either high or low and out of the trim region. As before, the sensor of the '216 patent must be manually adjusted in order to synchronize actual vehicle ride height with the sensor output.
It is an object of the present invention to provide an automotive suspension position sensor which may be calibrated remotely from the sensor and/or the vehicle.
It is a further object of the present invention to provide an automotive suspension position sensor which may be calibrated by means of a microprocessor.
It is yet a further object of the present invention to provide a suspension position sensor system which may be periodically recalibrated by a control system within the vehicle.
It is an advantage of the present system that a sensor system according to this invention will be able to compensate for drift of the output signal of the sensor.
Other objects, features and advantages of the present invention will become apparent to the reader of this specification.